Not that I know of, but you may be able to set up a bot to data-scrape the number of comments off the HTML and post them manually. I'll see what I can do.
Okay, but I know pretty much nothing about bots.
If someone wants to jump deeper into this: What about some kind of script that counts how many times a page is listed in Special:AllPages in namespace 1 (talk) would work here. Assuming message walls are enabled, every comment will be listed as a special @comment 'sub' to the mainspace pages.
Read all lines from Special:AllPages?namespace=1 and split the string at / If your wiki has a large amount of pages you have to keep in mind Special:AllPages will split the page and you will have to read multiple separate pages.